Conventional particulate filters for trapping particulate matter (PM) that is present in exhaust gas of an internal combustion engine include wall-flow particulate filters wherein first passages, the upstream end of which is blocked by plugs, and second passages, the downstream end of which is blocked by plugs, are disposed alternately, and wherein porous partition walls are disposed between the first passages and the second passages.
Wall-flow particulate filters that have been proposed include wall-flow particulate filters provided with through-holes in plug portions of the second passages (see, for instance, Patent literature 1). Other wall-flow particulate filters that have been proposed include wall-flow particulate filters that support a metal of lower electronegativity than that of calcium (Ca) (see, for instance, Patent literature 2). Further instances of proposed wall-flow particulate filters include filters in which a catalyst support layer is formed in part of the upstream side of the wall faces of passages (see, for instance, Patent literature 3).
Patent literature 1: Japanese Patent Application Publication No. 2004-130229 (JP 2004-130229 A)
Patent literature 2: Japanese Patent Application Publication No. 2001-12229 (JP 2001-12229 A)
Patent literature 3: International Patent Application No. 2008/126331 (WO 2008/126331)